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Tag: api 598

All articles tagged with "api 598".

All Cost Estimating Supplier Qualification Digitisation Contracts & Post Award Risk & Resilience Process Excellence RFQ & Tendering Supplier Relationships

Blueprint style graphic: a control valve beside a log scale of allowed seat leakage for a four inch valve: class IV about 535 millilitres a minute, class VI 1.7, class V 0.2, with a bubble column for the class VI air test

RFQ & TenderingFor procurement

Valve Seat Leakage Classes Explained: FCI 70 2, API 598 and ISO 5208

What control valve leakage classes II to VI allow, how API 598 and ISO 5208 rate isolation valves, and how to specify shut off in an RFQ so bidders quote the same tightness.

5 min read30 Oct 2026